Circadian rhythm of peripheral perfusion during 10-day hypoxic confinement and bed rest.

Autor: McDonnell AC; Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia, adam.mcdonnell@ijs.si., Eiken O, Mekjavic PJ, Mekjavic IB
Jazyk: angličtina
Zdroj: European journal of applied physiology [Eur J Appl Physiol] 2014 Oct; Vol. 114 (10), pp. 2093-104. Date of Electronic Publication: 2014 Jun 19.
DOI: 10.1007/s00421-014-2923-9
Abstrakt: Introduction: Future planetary habitats will be hypobaric and hypoxic to reduce the risk of decompression sickness during preparation for extra-vehicular activities. This study was part of a research programme investigating the combined effects of hypoxia and microgravity on physiological systems.
Purpose: We tested the hypothesis that hypoxia-induced peripheral vasoconstriction persists at night and is aggravated by bed rest. Since sleep onset has been causally linked to nocturnal vasodilatation, we reasoned that hypoxia-induced vasoconstriction at night may explain sleep disturbances at altitude. Peripheral perfusion alterations as a consequence of bed rest may explain poor sleep quality reported during sojourns on the International Space Station.
Methods: Eleven males underwent three 10-day interventions in a randomised order: (1) hypoxic ambulatory confinement; (2) hypoxic bed rest; (3) normoxic bed rest. During each intervention we conducted 22-h monitoring of peripheral perfusion, as reflected by the skin temperature gradient. Measurements were conducted on the first (D 1) and last day (D 10) of each intervention.
Results: All interventions resulted in a decrease in daytime toe perfusion from D 1 to D 10. There was no difference in the magnitude of the daytime reduction in toe perfusion between the three interventions. There was a significant vasodilatation of the toes in all interventions by 11 pm. The fingertips remained well perfused throughout.
Conclusions: Daytime vasoconstriction induced by hypoxia and/or bed rest is abolished at night, lending further support to the theory that changes in peripheral skin temperature may be functionally linked to sleep onset.
Databáze: MEDLINE
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